Resection of highly functionally connected glioma regions predicts long-term cognitive preservation

Background. Glioma surgery requires balancing maximal tumor resection against preservation of neurological and cognitive function. Intraoperative direct electrical stimulation guides this balance but is invasive and not always feasible. Preoperative magnetoencephalography (MEG) can identify tumor regions with high functional connectivity (HFC) to the rest of the brain. These HFC areas contain more malignant glioma cells and relate to poorer short-term outcome when resected. We aimed to determine whether HFC voxel resection relates to postoperative neurological and cognitive outcomes. Methods. In this preregistered analysis, 54 adults with diffuse glioma underwent resting-state MEG before resection. Imaginary coherence identified voxels with significantly higher connectivity against their contralateral controls, and these HFC voxels within the resection cavity were counted. Neurological status was assessed at short-term (~1 week) and long-term (~1 year) follow-up, and neuropsychological assessment took place at baseline and long-term follow-up. Logistic regressions related resected HFC voxels to decline at each timepoint, adjusting for Karnofsky performance status, sex and resectability index. Results. Resected HFC voxels were not associated with neurological decline at short-term (48% declined; odds ratio [OR] 0.98, P = .50) or long-term follow-up (27% declined; OR 0.99). For cognition, more resected HFC voxels were associated with less long-term decline (48% declined; OR 0.85, P = .02); a binarized analysis was consistent (OR 0.076, P = .01), indicating that tumor volume did not drive this result. Conclusions. Resecting more HFC voxels associates with preserved long-term cognition, without apparent neurological cost. Non-invasive MEG connectivity mapping may help optimize the onco-functional balance in glioma surgery.